Klotski Puzzle

Klotski (from Polish klocki—wooden blocks) is a sliding block puzzle thought to have originated in the early 20th century. The name may refer to a specific layout of ten blocks, or in a more global sense to refer to a whole group of similar sliding-block puzzles where the aim is to move a specific block to some predefined location. In most Klotski puzzle, the largest block must be moved to the bottom middle location so that it can be slid over the border, without any of the other blocks being removed in this way.